Electromagnetic door chime structure



May 10, 1966 J. DOGGART ELECTROMAGNETIC DOOR CHIME STRUCTURE 2 Sheets-Sheet 1 Filed Oct. 31, 1962 IN VE N TOR JOHN fiaeamer 5y flaw 5M l4 TTORNEYS May 10, 1966 J. DOGGART ELECTROMAGNETIC DOOR GHIME STRUCTURE 2 Sheets-Sheet 2 Filed 001;. 31, 1962 INVENTOR 5 WW AN WW 0%" NM Z Y 5 United States Patent O 3,251,056 ELECTROMAGNETIC DOOR CHIME STRUCTURE John Doggart, Tytherington, Macclesfield, England, as-

signor to V. & E. Friedland Limited, Macclesfield, England, a British company Filed Oct. 31, 1962, Ser. No. 234,319 Claims priority, application Great Britain, Nov. 16, 1961,

4 Claims. (Cl. 340-392) This invention relates to chimes.

According to one aspect of the invention, there is provided a chime comprising a tone bar having two arms inclined, preferably at right angles, relative to each other and striking means for striking one of the arms so that the chime will emit a note. Preferably the arm which is struck is shorter than the other arm. The tone bar is preferably carried by means engaging the said other.

thereof will now be described by way of example with reference to the accompanying drawings, in which:

. FIGURE 1 is a front view partly in section of a chime of the invention with the cover partly removed,

FIGURE 2 is a section on line 2-2 of FIGURE 1,

FIGURE 3 is a section on :line.33 of FIGURE 1,

FIGURE 4 is a back view of the chime, and

FIGURE 5 is a detail of a modification.

Referring now to the drawings, a chime of the invention comprises a cylindrical casing including a one piece, molded thermoplastic, semi-cylindrical base part 11 and a one piece, molded thermoplastic cover 12 of a contrasting color, e.g. the base part 11 may be black and the cover 12 white. The base part 11 has a mounting base 14 molded integrally therewith. Also molded integrally with the base part are two pairs of tone bar supports 15 and 16 which project beyond the side faces 17 of the base part 11 (see FIGURE 3) to serve also as side locations for the cover 12. A pair of ice-operating latch parts 18 are formed respectively on the end faces 21 of the base part and in the end faces 22 of the cover to hold the latter on the base part 11.

The chime further comprises two tone bars 23 and 24 tuned respectively to Gli(830.6l c./s.) and E(659.26 c./s.). Each tone bar comprises a long main arm 25 and a short end arm 26 bent at right angles thereto and the tone bars 23 and 24 are so arranged that the arms 25 and 26 lie at least partially along lines which define a rectangle. The two tone bars 23 and 24 are supported respectively by the two pairs of tone bar supports 15 and 16 which pass through openings 27 in the longer arms 25 of the tone bar, which openings are located at the nodes of the tone bars. Soft rubber gong supports 28 are interposed between .the tone bar supports and the tone bar. The tone bars 23, 24 are suspended at their upper nodes (indicated generally at 29) while the lower node (indicated generally at 31) is free of the gong supports (see FIGURE 1).

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Carried'by the mounting base 14 by means of retaining lugs 32 and projecting within the rectangle defined by the arms 25, 26 of, the tone bars is a U-shaped soft iron frame 33 (see FIGURE 2). The frame 33 carries a solenoid 34 wound on to a hard brass tube 35 which has its axis parallel to the longer arms 25 and perpendicular to the shorter arms 26 of the tone bars. A soft iron plunger 36 is slidable'within the tube 34. Nylon striker caps 38a and 38b are swaged'on to each end of the plunger 36. These striker caps 38a and 38b are in line with and are adapted to strike the ends of the shorter arms 26. A return spring 39 abutting against the plunger 36 and an arm 40 integral with the base urges the plunger 36 upwardly away from the shorter arm 26 of tone bar 25, which is below the solenoid 34.

Four sound apertures 41 are provided in the base part 12 and adjacent the antinode of major vibration between the supports of the tone bars.

The wires 45 from the solenoid 34 lead to two terminals 46 carried on the mounting base 14 by means of self tapping screws 47. Mounting holes 48 countersunk at each end are provided through the mounting base 14 as is a wiring channel 49 for external wire connections.

On energisation of the solenoid 34, the plunger 36 is drawn upwardly into the tube 35 carrying with it the spring 39 until the striker cap 38a strikes the shorter arm 26 of the tone bar 23. When the solenoid 34 is deenergised, the plunger 36 falls under gravity until the other striker cap 385 strikes the arm 26 of the other tone bar 24. The spring 39 then lifts the plunger off this arm. v

The cylindrical casing 10 is tuned to a frequency which is a compromise between the frequencies of the tone bars 23, 24 and, because of the'location of the sound apertures 42, 43 adjacent the antinodes of major vibration of'the tone bars, the casing 10 will provide satisfactory resonating chamber for the tone bars. The resonating chamber may be improved by stepping the connecting faces of the base and cover as shown in FIGURE 5 to reduce the possibility of unwanted air leakage.

By means of the design hereinbefore described, a twotone chime is contained within the cylindrical shape of a relatively small diameter and of pleasing appearance.

I claim:

1. A compact door chime comprising a base structure, a pair of L-shaped tone bars each having a long arm and a short arm, a core armature plunger and a coil, said core armature plunger and coil forming an electromagnetically operated double ended tone bar striker, support means on said base supporting said coil and core armature plunger with their axes longitudinally parallel to said base, further support means extending from said base and supporting said L-shaped tone bars with the long arms of said tone bars on opposite sides of said coil and parallel to said coil, said short arms of said L- shaped tone bars spaced from and overlying opposite ends of said coil, said core armature being operable in opposite directions towards first one and then the other of the ends of said coil to alternately strike the short arms of the L-shaped tone bars.

2. A door chime as defined in claim 1 including a cylindrical housing incorporating said support means and encasing said tone bars and said striker, said housing having a pair of main sound apertures therein and being tuned to serve as a resonating chamber for said tone bars.

3. A door chime as defined in claim 2 wherein said further support means engage the long arms of the respective tone bars at the node positions thereof.

4. A door chime as claimed in claim 2 wherein the sound apertures are located in the cylindrical part of the housing adjacent the antinodes of major vibrations of the longer arms of the tone bars.

References Cited by the Examiner UNITED STATES PATENTS Green et al. 340-392 McMullen 340-392 Rinker 340-392 Rinker 340-392 

1. A COMPACT DOOR CHIME COMPRISNG A BASE STRUCTURE, A PAIR OF L-SHAPED TONE BARS EACH HAVING A LONG ARM AND A SHORT ARM, A CORE ARMATURE PLUNGER AND A COIL, SAID CORE ARMATURE PLUNGER ANC COIL FORMING AN ELECTROMAGNETICALLY OPERATED DOUBLE ENDED TONE BAR STRIKER, SUPPORT MEANS ON SAID BASE SUPPORTING SAID COIL AND CORE ARMATURE PLUNGER WITH THEIR AXES LONGITUDINALLY PARALLEL TO SAID BASE, FURTHER SUPPORT MEANS EXTENDING FROM SAID BASE AND SUPPORTING SAID L-SHAPED TONE BARS WITH THE LONG ARMS OF SAID TONE BARS ON OPPOSITE SIDES OF SAID COIL AND PARALLEL TO SAID COIL, SAID SHORT ARMS OF SAID LSHAPED TONE BARS SPACED FROM AND OVERLYING OPPOSITE ENDS 